I received a code with the 4th edition of Getting to Know ArcGIS for a 180 day trial version of ArcGIS. I have downloaded the software, but somehow accidentally selected "concurrent user" rather than "single user." I managed to change that using ArcGIS Administrator by following directions posted here. I ran the authorization wizard and it said it was successful, but then it reverted to concurrent user and ArcMap would not launch. I re-read the post and ran ArcGIS Administrator as admin and now it is staying with "single user." However, now when I run the authorization wizard with the same code from the email, it says "authoization failed." What do I do now?
You might want to move your content here... ArcGIS for Desktop Installation support
I will flag V Stuart Foote and Curtis Price since there isn't any specific document on that site but discussion on installation that may match your case.
You may want to check this thread Student Version - ArcGIS Error Message Which talks about the 180-day authorization too. see the section
For Esri Press or Campus Agreement trial/evaluation Authorization numbers--each user/student must individually register their Authorization number here:
http://www.esri.com/StudentEdition
--or--
ArcGIS 90 or 180-Day Trial for Your Workbook
Esri Press | GIS Books & Tutorials - Buy Books Online
Once the Authorzation code is activated--the Single Use authorization is exactly the same for trial/evaluation (EVA) or commercial (ESU) Single Use seats. It is easiest to accomplish when you have a network connection to exchange the https port 443 traffic using the "Authorize now via the internet"
Authorizing ArcGIS single-use products and features—Help | ArcGIS for Desktop
What is the availability status?
If possible attach the screenshot.